Method of capsulating



March 1955 N. N. PLOURDE 2,702,923

METHOD OF-CAPSULATING Filed April 11, 1952 3 Sheets-Sheet 1 FIG IINVENTOR NEAL .N. PLOURDE I: BY

ATTORNEY March 1, 1955 N. N. PLOURDE METHOD OF CAPSULATING 3Sheets-Sheet 2 Filed April 11, 1952 FIG 2A INVENTOR f NEAL-N. PLO RD MWATTOR .\'EY

March 1955 N. N. PLOURDE METHOD OF CAPSULATING 3 Sheets-Sheet 3 FiledApril 11, 1952 1.\ ENTUR NEAL N. PLOURDE,

A T71 )RNEY United States Patent- METHOD OF CAPSULATING Neal N. Plourde,Detroit, Mich., assignor to Gunnell Capsulations, Inc., Van Dyke, Mich.,a corporation of Michigan Application April 11, 1952, Serial No. 281,739

7 Claims. (Cl. 18-48) This invention relates to improving the characterof capsule coatings or shells.

Capsule shells of the character here involved are applied in liquid orfluid condition to a measured quantity of capsule fill or contentmaterial, and thereafter treated to harden and finish the coating.According to the present invention the capsule with its fluid orsemi-fluid coating or shell is rotated in the treating medium tomaintain the shell of uniform thickness until it has hardenedsufiiciently to lose its capacity to flow. The capsule shell while in asoft but non-fluid condition may also be formed into non-sphericalshape. I

The further nature and details of the invention Will readily appear fromthe following description of illustrative embodiments of the inventionshown in the accompanying drawings.

In said drawings:

Fig. 1 is a sectional elevation of a treating receptacle equipped withcapsule rotating means in the form of a pair of belts;

Fig. 1A is a sectional View taken along the line A--A 1n Fi 1;

l ig. 2 is a view similar to Fig. 1 wherein a single belt and astationary surface cooperate to rotate the capsule;

Fig. 2A is a sectional view taken along the line A-A in Fi 2' l ig. 3 isa view similar to Fig. 1 showing opposed belts arranged both to rotatethe capsule and to form 1t1nto nonspherical shape;

Fig. 4 is a view similar to Fig. 2 showing the belt arranged to travelin a horizontal direction; and

Fig. 5 is a view similar to Fig. 1 wherein a series of rollers insteadof belts are employed to rotate the capsules.

Seamless capsules may be formed, as in Gunnell Patent 2,342,661, byapplying a coating or covering fluid form around a quantity of capsulecontent material, and then hardening or setting the coating. In the caseof thermoplastic shell materials, such as gelatin, thrs is doneinitially by cooling the shell in a cooled liquid bath through which thecapsule is passed. The fluid shell material may be initially applied invarious ways such as by passing a globule of content material through abath of gelatin in liquid condition and collecting a seamless layer ofshell material directly on the globule, as in said Gunnell patent. Inanother method shown in Mabbs Patent 2,379,816, a measured quantity ofcontent material is extruded inside a tubular stream of shell material.Globules of the composite material are dropped into a cooling bath toharden the shell. The surface tension of the content and shell materialscauses the capsules to assume spherical shapes. The invention is notlimited to any particular way of initially applying a fluid coating tothe content material.

Since the coating or shell, however applied, remains fluid or semi-fluidfor an appreciable time after it has been applied to the contentmaterialand has assumed a spherical shape, the forces acting on its cause theshell to thin off at the top of the capsule and collect adjacent thebottom of the capsule as it passes through the cooling or setting bath.This may be caused by gravity, unequal cooling of the shell, etc.Capsules with a coating of nonuniform thickness will often be defective(e. g., the thin portion of the shell is weak and often breaks), but inany case they are not marketable.

According to the present invention the shell material is prevented fromsegregating and is maintained uniformly distributed over the contentmaterial by rotating the capsule until the shell material has hardenedto non-fluid condition. Various means for rotating the capsule may beemployed. These are not limited to the illustrative means. According tothe means here illustrated, substantially as soon as the capsule entersthe cooling and hardening bath it is placed in control of a rotatingdevice and is rotated thereby about a generally horizontal axis at arate sulficient to prevent segregation of the shell material. One formof rotating device is a belt 10 moving in the direction of travel of thecapsule which transmits to the capsule as it is suspended in thehardening bath suflicient force to rotate it. The layer of liquiddragged along by the moving belt may exert sufficient frictional forceto rotate the capsule without actual contact of the capsule with thebelt itself. Various means may be employed to maintain an operativecontact with the capsule. In Fig. 1, for example, another oppositelytraveling belt is placed opposite the main belt 10 and spaced therefroma distance sufficient to receive the capsule between the adjacent runsof the belts. Substantial frictional contact with the capsule is notnecessary because the belts in moving through the cooling bath drag afilm of liquid with them which film is suflicient to cause rotation ofthe capsule. Where, as in the present case, the capsule rises throughthe hardening bath, the upwardly traveling run of the belt, in this casebelt iii, preferably travels slightly faster than the downward travel ofthe opposite belt 11, thereby to assist in moving the capsule upwardlythrough the bath. For other directions of capsule travel, i. 'e., down,horizontally, etc., the belt moving in the direction of capsule travelshould have the higher rate of speed. Preferably the capsule is placedbetween the belts to be rotated as soon as practicable after it entersthe cooling bath.

A jet of liquid or circlulation of the liquid may also be employed tocause the capsule to rotate through the apparatus.

The rate of rotation of the capsule need not be sufiicient to create anysubstantial centrifugal forces since the shell material is maintained ata uniform thickness simply by continuously changing the position of thecapsule so as to counteract any tendency of the shell material todistribute itself non-uniformly.

The belts may be formed of a plurality of metal links which present asmooth surface to the capsules or they may be made of flexible metal orfabric. Preferably the belts are supported in such way that theirspacing may be adjusted and their rate of speed regulated. The length ofrun of the belts should depend somewhat on the rate of travel of thecapsule through the bath. Generally such length varies from 8 to 16inches. For travel of the capsule through a horizontal bath, the beltswould be appropriately re-arranged to follow the direction of travel ofthe capsule.

Fig. 1 illustrates details of one illustrative adjusting means. Theseveral pairs of belt pulleys 12 and .13 are supported on verticalmembers 14 which are in turn carried on transverse members 15 extendingacross the receptacle 16 containing the bath of cooling or hardeningliquid. The belt runs are laterally spaced or adjusted, in this case, bymeans of slots 17 in the plate members 14 through which supportingscrews or bolts connecting the same to the transverse members 15, pass.The belt pulleys l2 and 13 are rotated in the same direction (therebycausing the adjacent runs of belts 10 and 11 to travel in oppositedirections) by shaft 18 through flexible driving elements such as chainsand sprockets. The driving means here represented at 19 is preferablycapable of variation in speed to adjust belt speeds.

Guide means, here shown in the form of rods 20 adjacent the edges of thebelts, prevent lateral escape of the capsules.

In cases of horizontal capsule travel the active run of the belt may bevery slightly above the liquid of the bath but having contactedtherewith initially to draw up a meniscus of liquid at both edges ofthebelt. This acts as guide means to prevent the capsule from movinglaterally out of the path of the belt. Fig. 4 illustrates onearrangement for horizontal travel, but it will be understood that withobvious rearrangement, the constructions shown in the other figures maybe employed for horizontal capsule travel.

After the shell material has hardened sufiiciently to render itnon-fluid, the capsule in its still plastic condition may then beprocessed to non-spherical form. This may be accomplished with thedevices shown in Fig. l by causing the belts and 11 to converge slightlyto exert compression on the capsules and elongate them in the direc tionof their axes into cylindrical or oblate spheroid form. For this purposethe entrance ends of the belts are spaced apart by the diameter of thecapsule plus about to ,4 inch and the exit ends are brought together soas to be spaced only about of the initial diameter of the capsule. Thecapsule remains under the control of the belts until it is hardenedsufficiently to maintain its elongated shape.

In cases where the capsule travels downwardly through hardening bath,the belts are advantageously adjusted for entry of the capsule at thetop instead of the bottom. In such case their directions of travel arereversed and their upper ends are spaced to receive the capsule, suchspacing being approximately the diameter of the capsule plus 6 to 4inch, depending upon the action on the capsule desired.

In Fig. 2 is illustrated a simple form of rotating device comprising asingle belt 21 located opposite a fixed or stationary surface 22. In thecase of upwardly traveling capsules the inner or active run of the belttravels upwardly and rotates the capsules over the fixed surface 22.Guide rods 23 prevent lateral escape of capsules. The thickness of thechannel through which the capsules pass may be adjusted by moving thefixed surface 22 either toward or away from the belt. Slots 24 areprovided for this purpose. By tapering the thickness of the passage thecapsules may be pressed after the shell material has as sumed anon-fluid state, to elongate the capsule.

Preferably guide members, such as the sheet metal guides 25 and 26 inFigs. 1 and 2 respectively are located at the entrance ends of the beltsto direct the capsules from their points of introduction into the bathinto operative relation with the belts. As here shown, such guides arecarried at the ends of guide rods 20.

In Fig. 3 a plurality of belts are shown which permit a greaterflexibility in the treatment given the capsule. The main belt 30 hasassociated with it a lower belt 31 and an independent upper belt 32capable of independent spacing and direction of travel. The belts arehere shown arranged for upward travel of the capsule. Belts 30 and 31are adjusted as in the case of the belts of Fig. l to rotate the capsuleand move it upwardly until the shell material is no longer fluid.Thereafter the capsule travels into the control of belts 30 and 32 whichare more closely spaced to exert compression on the capsule until it ishardened. If the adjacent runs of the belts travel in oppositedirections the capsule will be rolled and compressed into an elongatedcylindrical form as heretofore explained. If the adjacent runs of thebelts 30 and 32 travel in the same direction, the capsule may becompressed into a flat lozenge or tablet shape. A deflector guard 33 islocated between the belts 31 and 32 to guide the capsules from one beltto the next to prevent their escape between the belts.

The aforesaid belts may advantageously be supported and driven in amanner similar to that illustrated in Fig. 1.

In Fig. 5 a different form of rotating means is shown comprising aseries of pairs of rolls whose adjacent surfaces travel in oppositedirections and cause the capsule to rotate as aforesaid. The rolls 41 ofone series may advantageously travel at a slightly higher speed thanthose of the other series 42 to assist in moving the capsules in thedesired direction of travel, i. e., in this case, upwardly. Deflectors43 are located between the rolls to prevent escape of capsules. Suitableguide means prevent escape of capsules.

It is clear from the foregoing that various means may be employed torotate and later compress the capsules if it be desired to give themnon-spherical shape.

Obviously the invention is not limited to the details of theillustrative process, since these may be variously modified. Moreover,it is not indispensable that all features of the invention be usedconjointly, since various features may be used to advantage in differentcombinations and sub-combinations.

Having described my invention, I claim:

1. In the method of making capsules in which the con tent material iscovered with a coating material in fluid condition, the steps ofintroducing the capsule thus coated into a liquid coating hardening bathand rotating the capsule while in the bath until the coating is innon-fluid condition by directing said capsules into close proximity withthe surface of a rotating member in said bath.

2. In the method of making capsules in which the content material iscovered with a coating material in fluid condition, the steps ofintroducing the capsule thus coated into a liquid coating hardening bathand rotating the capsule while in the bath to prevent segregation of thecoating and maintaining a uniform thickness of the coating until thelatter has hardened to non-fluid condition by bringing said capsulesinto rolling contact with the surface of a rotating member in said bath.

3. In the method of making capsules in which the content material iscovered with a coating material in fluid condition, the steps ofintroducing the capsule thus coated into a liquid coating hardening bathand rotating the capsule while in the bath until the coating is innon-fluid condition, and then before the coating has hardened but afterit has lost its fluidity, shaping the capsule into non-spherical formand maintaining such form until the coating has hardened sufficiently tomaintain such non-spherical form.

4. In the method of making capsules in which the content material iscovered with a coating material in fluid condition, the steps ofintroducing the capsule thus coated in spherical form into a liquidcoating hardening bath and rotating the capsule while in the bath untilthe coating is in non-fluid flexible condition, and then shaping thecapsule into non-spherical form and maintaining such form until thecoating has hardened to self-sustaining condition.

5. In the method of making capsules in which the content material iscovered with a coating material in fluid condition, the steps ofintroducing the capsule thus coated into a liquid coating hardeningbath, passing the capsule through the bath and simultaneously rotatingit until the coating is in non-fluid condition by directing the capsulesbetween a pair of surfaces in said bath which are spaced apart generallyto correspond with the diameter of the capsules and at least one of saidsurfaces being caused to rotate.

6. In the method of making capsules in which the content material iscovered with a coating material in fluid condition, the steps ofintroducing the capsule thus coated into a liquid coating hardeningbath, causing said capsules to travel between a pair of closely spacedbelts in said bath which are caused to travel in opposite directions,and causing said belts to rotate said capsules.

7. In the method of making capsules in which the content rnaterial iscovered with a coating material in fluid condition, the steps ofintroducing the capsule thus coated into a liquid coating hardeningbath, directing a tangential force against at least one side of thecapsule while in the bath and before the coating has become non-fluid tocause the capsule to rotate and continuing the application of saidtangential force to said capsule until the coating is in a non-fluidcondition.

References Cited in the file of this patent UNITED STATES PATENTS2,332,671 Scherer Oct. 26, 1943 2,342,661 Gunnell Feb. 29, 19442,531,986 Pile et a1. Nov. 28, 1950

